Method of pre-treating molybdenite containing copper

ABSTRACT

Disclosed is a method of pre-treating molybdenite containing copper. The method includes mixing molybdenite containing copper with sulfuric acid, performing a sulfation reaction through a heating process after the mixing process is performed, performing a water leaching process by putting and stirring water after the sulfation reaction is performed, separating a cake from liquid after the water leaching process is performed, and drying the separated cake.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2013-0146129 filed on Nov. 28, 2013, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1) Field of the invention

The present invention relates to a method of pre-treating molybdenite (MoS₂) containing copper, capable of removing copper from low-grade molybdenite.

2) Background of Related Art

Molybdenum (Mo) improves a hot creep characteristic of steel, prevents temper brittleness of the steel, and enhances corrosion resistance of the steel, so that Mo serves as an important element to manufacture heat resisting steel or an important alloying element to manufacture corrosion-resisting steel. A copper (Cu) content in ferro-molybdenum (Mo) for steel is limited to 0.5% or less.

Molybdenite (MoS₂) is an economical primary source material of Mo. Although the molybdenite generally has the concentration of Mo in the range of about 0.05% by weight to 0.1% by weight, so that the molybdenite represents low concentration among iron ores, a sulfide, Cu, and iron can be easily retrieved through a floatation process due to the characteristic of sulfuric ore and concentrated.

To reduce the Cu content of the molybdenite to 0.5% or less only through an ore dressing process is difficult because Cu is sulfuric ore also. Since a Mo retrieval ratio may be degraded, it is difficult to reduce the Cu content from the molybdenite having a high Cu content. Nevertheless, the molybdenite having the high Cu content has been still produced and sold.

Ferro-molybdenum for steel may be manufactured from low-grade molybdenite containing Cu by performing calcinations for molybdenite to prepare an oxide, leaching the oxide by a dilute sulfuric acid solution to remove Cu, and then performing a filtering process, a drying process, and a heat reduction process. According to the above scheme, Mo is wasted in the leaching by sulfuric acid because Mo is significantly dissolved in an aqueous solution. Therefore, the process of retrieving the Mo is required. In the leaching by the sulfuric acid, molybdenum trioxide (MoO₃) reacts with water so that the molybdenum trioxide exists in the form of molybdic acid. Accordingly, energy is significantly consumed when drying the moisture of a filtered cake. In order to compensate for the above disadvantage, a method to remove Cu in a sulfide state through the leaching process has been developed. U.S. Pat. No. 1,895,811 (published on Jan. 31, 1933) relates to a process of treating ores. According to the patent, a high-pressure vessel is not required, and the process is simple. However, when strong sulfuric acid is applied to molybdenite and the result is treated at a high temperature, as a temperature is raised, the reaction rate and the reaction ratio are increased, so that the surface of molybdenite is oxidized and leached together with Cu by the aqueous solution. Therefore, a process of increasing the copper removal ratio and minimizing the oxidation of Mo must be developed.

SUMMARY OF THE INVENTION

The present invention provides a method of pre-treating molybdenite (MoS₂) containing copper (Cu), capable of removing only copper (Cu) while minimizing the oxidation of molybdenum (Mo) when low-grade molybdenite (MoS₂) containing a copper sulfide reacts with sulfuric acid.

The objects of the present invention are not limited to the above-mentioned objects, and other objects will be clearly understood by those skilled in the art.

In order to accomplish the above object, there is provided a method of pre-treating molybdenite (MoS₂) containing copper. The method includes mixing molybdenite containing copper with sulfuric acid, performing a sulfation reaction through a heating process after the mixing process is performed, performing a water leaching process by putting and stirring water after the sulfation reaction is performed, separating a cake from liquid after the water leaching process is performed, and drying the separated cake.

In this case, the sulfation reaction is performed at a temperature of 180° C. to 240° C. for time of 20 minutes to 80 minutes.

The sulfuric acid is mixed with the molybdenite at an equivalent ratio of 0.9 to 1.8 with respect to the molybdenite.

In addition, the sulfation reaction is performed at a temperature of 210° C. to 240° C. for time of 40 minutes to 80 minutes

The water includes at least one selected from the group consisting of distilled water, deionized water, hard water, and heavy water.

Further, the method of pre-treating molybdenite containing copper further includes performing a floatation process with respect to the molybdenite before the molybdenite is mixed with the sulfuric acid.

As described above, according to the present invention, in order to manufacture ferro-molybdenum (Mo) for steel from low-grade molybdenite containing copper (Cu), the sulfation reaction temperature and time are adjusted when treating molybdenite to prevent a conventional problem that Mo is leached by an aqueous solution, and the copper removal ratio can be improved.

In addition, only the copper sulfide is changed to a copper sulfate and leached by water to be removed. Accordingly, when comparing with the related art of performing the leaching by sulfuric acid after calcinations, the solid-liquid separation can be more easily performed, and the cost to retrieve molybdenum from wasted acid can be reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart showing a method of pre-treating MoS₂ containing Cu according to the present invention.

FIG. 2 is a graph showing a boiling point according to the concentration of H₂SO₄ in a water-sulfuric acid system.

FIG. 3 is a graph showing a Cu removal ratio according to a sulfuric acid content in the method of pre-treating MoS₂ containing Cu according to the present invention.

FIG. 4 is a graph showing the result of an X-ray diffusion analysis for MoS₂ according to a sulfuric acid content in the method of pre-treating MoS₂ containing Cu according to the present invention.

FIG. 5 is a graph showing the change in the concentration of Cu in MoS₂ as a function of a sulfation reaction temperature and a sulfation reaction time in the method of pre-treating MoS₂ containing Cu according to the present invention.

FIG. 6 is a graph showing the change of a dissolved molybdenum rate according to a sulfation reaction temperature and a sulfation reaction time in the method of pre-treating MoS₂ containing Cu according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an example embodiment of the present invention will be described in detail with reference to accompanying drawings.

The advantages, the features, and schemes of achieving the advantages and features of the present invention will be apparently comprehended by those skilled in the art based on the embodiments, which are detailed later in detail, together with accompanying drawings.

The present invention is not limited to the following embodiments but includes various applications and modifications. The embodiments will make the disclosure of the present invention complete, and allow those skilled in the art to completely comprehend the scope of the present invention. The present invention is only defined within the scope of accompanying claims.

In addition, the details of the generally-known technology that makes the subject matter of the present invention unclear will be omitted in the following description.

The present invention provides a method of pre-treating molybdenite (MoS₂) containing copper according to the present invention including a step of mixing molybdenite containing copper (Cu) with sulfuric acid (H₂SO₄), a step of performing a sulfation reaction by heating the result after the mixing step, a step of performing a water leaching process by putting water into the result after the sulfation reaction and stirring the result, a step of separating a cake from a liquid after the water leaching process, and a step of drying the separated cake.

According to the method of pre-treating molybdenite containing copper according to the present invention, after preparing copper sulfate using copper contained in molybdenite by making the reaction between low-grade molybdenite containing copper sulfide and sulfuric acid, a water leaching process is performed to remove copper. In this case, a temperature and time are adjusted in the reaction with the sulfuric acid, thereby increasing a copper removal ratio and minimizing the oxidation of molybdenum.

FIG. 1 is a flowchart showing a method of pre-treating molybdenite containing copper according to the present invention. Hereinafter, the present invention will be described in detail with reference to FIG. 1

The method of pre-treating molybdenite containing copper according to the present invention includes a step (S100) of mixing molybdenite containing copper with sulfuric acid.

According to the method of pre-treating molybdenite containing copper according to the present invention, the molybdenite containing copper includes chalcopyrite (CuFeS₂), chalcocite (Cu₂S) and bornite (Cu₅FeS₄), and copper sulfate can be prepared through the reaction between the minerals and sulfuric acid. In this case, before mixing the molybdenite with the sulfuric acid, a step of performing a floatation process is additionally provided, in which a mineral having a hydrophobic surface among molybdenite particles adheres to the surface of a bubble and floats onto a solution surface, and a mineral having a hydrophilic surface among the molybdenite particles remains in a solution, so that the mineral having the hydrophobic surface can be separated from the mineral having the hydrophilic surface. In addition, a step of crushing and pulverizing the molybdenite is additionally provided to more improve the reactivity between the molybdenite and the sulfuric acid.

In addition, the molybdenite must be uniformly mixed with the sulfuric acid. When the whole molybdenite is not sufficiently immersed into the sulfuric acid, water is added to the mixture so that the molybdenite can be uniformly mixed with the sulfuric acid.

The method of pre-treating molybdenite containing copper according to the present invention includes a step (S200) of making a sulfation reaction by heating the result after the mixing step.

In this case, an amount of added sulfuric acid is required to the extent that the sulfuric acid reacts with all elements, such as alkali metal or alkali earth metal oxide contained in low-grade molybdenite as well as sulfides including Cu, Fe, and Zn, which may react with the sulfuric acid. The amount of sulfuric acid may be added or subtracted depending on a source material or a reactor because the reactivity between the sulfuric acid and the elements is variously represented according to an amount of sulfuric acid, which is evaporated and lost, and the types of impurities. According to the method of pre-treating molybdenite containing copper according to the present invention, the sulfuric acid is preferably mixed with molybdenite at an equivalent ratio of 0.9 to 1.8 with respect to the molybdenite. If the sulfuric acid is mixed at the equivalent ratio of 0.9 or less, the copper removal ratio in the molybdenite may be lowered. If the sulfuric acid exceeds the equivalent ratio of 1.8, molybdenum contained in the molybdenite may be leached.

FIG. 2 is a graph showing a boiling point according to the concentration of sulfuric acid (H₂SO₄) in a water-sulfuric acid system. It can be recognized from FIG. 2, that the maximum temperature allowing the treatment using sulfuric acid under an atmospheric pressure is 330° C. which is a eutectic point of about 98.3% by weight of sulfuric acid and water. For reference, about 90% by weight of sulfuric acid has the boiling point of 255° C.

If molybdenite makes sulfation-reaction with sulfuric acid, copper contained in molybdenite is changed to copper sulfate as shown in following chemical equations 1, 2, and 3.

1/2CuS₂+2H₂SO₄→CuSO₄+1/2S+2H₂O+SO_(2↑)  [Reaction Formula 2]

1/4CuFeS₄+3H₂SO₄→5/4CuSO₄+1/4FeSO₄+S+2H₂O+3/2SO_(2↑)  [Reaction Formula 3]

Following table 1 shows heat of reaction (ΔH), Gib's free energy (ΔG), and equilibrium constant (K) generated when CuFeS₂, Cu₂S and Cu₅FeS₄ contained in molybdenite react with sulfuric acid. As shown in table 1, as a temperature is raised, a reaction ratio (equilibrium constant) is increased, and it can be understood from the heat of reaction that a weak endothermic reaction (ΔH>0) occurs.

TABLE 1 Temperature (° C.) 180 210 225 240 300 CuFeS₂ ΔH 1.072 1.063 1.066 1.078 1.301 (Kcal/mole) ΔG −16.078 −17.214 −17.781 −18.349 −20.629 (Kcal/mole) Equilibrium 5.7E07 6.1E07 6.3E07 6.5E07 7.4E07 constant (K) Cu₂S ΔH 5.59 5.48 5.43 5.4 5.49 (Kcal/mole) ΔG −8.18 −9.09 −9.54 −9.99 −11.79 (Kcal/mole) Equilibrium 8.8E07 1.3E07 1.5E07 1.8E07 3.1E07 constant (K) Cu₅FeS₄ ΔH 8.644 8.579 8.135 8.043 8.019 (Kcal/mole) ΔG −14.613 −16.151 −16.908 −17.66 −20.656 (Kcal/mole) Equilibrium 1.1E07 2.0E07 2.6E07 3.3E07 7.5E07 constant (K)

If molybdenite reacts with sulfuric acid, the surface of the molybdenite may be oxidized according to chemical equation 4 or 5, and the oxidized molybdenite is significantly dissolved in water.

MoS₂+2H₂SO₄→MoO₂+2S+2H₂O+2SO_(2↑)  [Reaction Formula 4]

MoS₂+3H₂SO₄→MoO₃+2S+3H₂O+3SO_(2↑)  [Reaction Formula 4]

Following table 2 shows heat of reaction (ΔH), Gib's free energy (ΔG), and equilibrium constant (K) generated in the oxidation between the molybdenite and the sulfuric acid. It can be recognized that a reaction ratio is increased as a temperature is raised even in the oxidation between the molybdenite and the sulfuric acid.

TABLE 2 Temperature (° C.) 180 210 225 240 300 MoS₂ + ΔH 36.79 36.88 36.92 36.97 37.28 2H₂SO₄ (Kcal/mole) ΔG −4.13 −6.84 −8.20 −9.56 −15.01 (Kcal/mole) Equilibrium 9.8E01 1.2E03 3.9E03 1.2E04 5.3E05 constant (K) MoS₂ + ΔH 54.15 54.13 54.13 54.13 54.37 3H₂SO₄ (Kcal/mole) ΔG −7.04 −11.09 −13.11 −15.14 −23.24 (Kcal/mole) Equilibrium 2.5E03 1.0E05 5.7E05 2.8E06 7.3E08 constant (K)

As described above, both of the copper sulfide and the molybdenite are increased in the reaction ratio as the temperature is raised. However, Cu and Mo make a difference in the reactivity from strong sulfuric acid. In other words, an oxide of Cu or Fe, which is a basic oxide, easily reacts with the sulfuric acid. To the contrary, an oxide of Mo, which is an acid oxide, does not easily react with the sulfuric acid. Similarly, in terms of a sulfide, a sulfide of Cu reacts with the sulfuric acid more easily than a sulfide of Mo reacts with the sulfuric acid. Therefore, if a reaction condition with the sulfuric acid is properly adjusted, most sulfides of Cu are changed to the copper sulfate, and MoS₂ may not react with the sulfuric acid. Accordingly, the sulfation reaction is preferably performed at the temperature of 180° C. to 240° C. for 20 minutes to 80 minutes. If the sulfation reaction is performed at the temperature of 180° C. or less, the copper removal ratio is lowered. If the sulfation reaction is performed at the temperature of more than 240° C., the leaching rate of Mo is increased, so that Mo must be retrieved from a leaching solution. In addition, if the sulfation reaction time is less than 20 minutes, Cu is not sufficiently removed from the molybdenite. If the sulfation reaction time is more than 80 minutes, Mo may be leached.

Both of batch and continuous sulfation reactors are possible. In the case of the batch sulfation reactor, a thin reactant layer is formed, and the whole reactant is maintained at a constant temperature. In the case of the continuous sulfation reactor, the whole temperature of the reactor is constantly maintained, and the reactant must plug-flow such that the residence time of the reactor is constantly maintained. The reactant subject to the sulfation reaction is preferably discharged and cooled at the temperature of 100° C. or less.

The method of pre-treating molybdenite containing copper according to the present invention includes a step (S300) of performing a water leaching process by putting water into the result after the sulfation reaction and stirring the result.

According to the method of pre-treating molybdenite containing copper of the present invention, copper sulfate and other impurities are leached and removed from the molybdenite subject to the sulfation reaction by using water in a leaching tank including a stirrer. The water may include at least one selected from the group consisting of distilled water, deionized water, hard water, and heavy water.

Next, the method of pre-treating molybdenite containing copper of the present invention includes a step (step S400) of separating a cake from a liquid after the water leaching process.

According to the method of pre-treating molybdenite containing copper of the present invention, a solid-liquid separation scheme is performed to separate a cake and liquid existing in the solution from each other after the water leaching process has been performed. In this case, the solid-liquid separation may be performed by filters such as a belt filter and a drum filter.

The method of pre-treating molybdenite containing copper of the present invention includes a step (S500) of drying the separated cake.

In order to remove moisture from the separated cake, the separated cake may be subject to the drying process.

In addition, the present invention provides a method of pre-treating molybdenite containing copper including a step of mixing molybdenite containing copper with sulfuric acid, a step of performing a sulfation reaction through a heating process at the temperature of 210° C. to 240° C. after the mixing step has been performed, a step of performing a water leaching process by putting water into the result after the sulfation reaction has been performed and stirring the result, a step of separating a cake from a liquid after the water leaching process has been performed, and a step of drying the separated cake.

According to the method of pre-treating molybdenite containing copper of the present invention, the sulfation reaction is performed at the temperature of 210° C. to 240° C. for 40 minutes to 80 minutes to remove Cu by 99% or more and retrieve Mo by 99.7% or more (see Experimental examples 2 and 3). In this case, the sulfuric acid is preferably mixed with molybdenite at an equivalent ratio of 0.9 to 1.8 with respect to the molybdenite. The reason for the limitation of the equivalent ratio has been already described above.

Embodiment 1 Pre-Treating of Molybdenite Containing Copper

Follow table 3 shows components and contents of concentrates obtained by performing a floatation process with respect to molybdenite collected from the Geum-um mine located at Hupoup, Uljin-gun, Gyeonsangbuk-do. A strong sulfuric acid, in which 20 g of molybdenite shown in table 3 and sulfuric acid were dissolved, was put into a 50 ml crucible, and sufficiently stirred by using a glass rod. Then, the sulfation reaction was performed by using a muffle furnace. The test sample was drawn into the crucible after the sulfation reaction had been performed and cooled. Then, the test sample was stirred in a 1000 ml flask having 200 ml of distilled water at the rate of 300 rpm and the temperature of 90° C. for 60 minutes and leached. The test sample was filtered by using a glass microfiber filter and dried at the temperature of 112° C. for 24 hours.

TABLE 3 Average Element Mo S Cu Fe Pb Zn MgO SiO₂ Al₂O₃ CaO Diameter (μm) Content 39.1 24.9 7.66 8.48 0.97 0.73 0.10 1.94 7.52 0.32 32.1 % by weight

Experimental Example 1 Analysis of Cu Concentration and Cu Removal Rate According to Content of Sulfuric Acid

In the method of pre-treating molybdenite containing copper according to the present invention, Cu concentration and a Cu removal rate according to sulfuric acid contents were analyzed and the results were shown in table 4, and FIGS. 3 and 4.

TABLE 4 Content of 180 ° C. 225 ° C. sulfuric Cu content Cu removal Cu content Cu removal acid (g) (% by weight) rate (%) (% by weight) rate (%) 2 7.4 3.4 7.51 4.5 4 7.23 6 7.05 8 8 6.7 13 5.1 22 16 3.61 49 0.16 97 32 2.53 85 0.05 99 64 0.53 95.4 0.03 99.6

As shown in table 4 and FIG. 3, the copper removal ratio was increased as the content of the sulfuric acid was increased in both cases that the sulfation reaction temperature was 180° C. and the sulfation reaction temperature was 225° C. (sulfation reaction time: 40 minutes). In the case that the sulfation reaction temperature was 225° C., 97% of copper removal ratio was represented when the sulfuric acid content was 16 g, and the copper removal ratio was increased as the sulfuric acid content was increased. Further, even though the same sulfuric acid content was provided, the copper removal ratio at the sulfation reaction temperature of 225° C. was higher than the copper removal ratio at the sulfation reaction temperature of 180° C.

In addition, FIG. 4 is a graph showing the result of an X-ray diffusion analysis for molybdenite according to a sulfuric acid content in the method of pre-treating molybdenite containing copper according to the present invention. Referring to FIG. 4, even though molybdenite and quartz were observed in molybdenite before the sulfation reaction, molybdenite, sulfur, and quartz existed in molybdenite after the sulfation reaction.

Experimental Example 2 Analysis of Cu Concentration According to Sulfation Reaction Temperature and Time

In the method of pre-treating molybdenite containing copper according to the present invention, Cu concentration according to sulfation reaction temperature and time was analyzed and the results were shown in table 5, and FIG. 5.

TABLE 5 Sulfation reaction 180° C. 210° C. 225° C. 240° C. 270° C. 300° C. 10 minutes 7.64 3.5 2.15 1.76 0.22 0.14 20 minutes 6.03 2.12 0.54 0.34 0.18 0.14 30 minutes 2.7 0.81 0.33 0.05 0.058 0.043 40 minutes 1.38 0.65 0.074 0.045 0.042 0.031 80 minutes 0.76 0.06 0.031 0.032 0.031 0.029

As shown in table 5 and FIG. 5, when the sulfation reaction was performed at the sulfation reaction temperature of 210° C. for the sulfation reaction time of 80 minutes, 0.06% by weight Cu remained. When the sulfation reaction was performed at the sulfation reaction temperature of 225° C. for the sulfation reaction time of 30 minutes, 0.33% by weight Cu remained. When the sulfation reaction was performed at the sulfation reaction temperature of 240° C. for the sulfation reaction time of 20 minutes, 0.34% by weight Cu remained. When the sulfation reaction was performed at the temperature of 270° C. and the temperature of 300° C. for the sulfation reaction time of 10 minutes, 0.22% by weight Cu and 0.14% by weight Cu remained, respectively, (H₂SO₄ content: 32 g). Accordingly, the Cu content of molybdenite can be reduced to 0.5% by weight by performing the sulfation reaction at the sulfation reaction temperature of 210° C. for 80 minutes. In addition, the Cu content of molybdenite can be reduced to 0.5% by weight when the sulfation reaction is performed at the sulfation reaction temperature of 225° C. for the sulfation reaction time of 30 minutes, at the sulfation reaction temperature of 240° C. for the sulfation reaction time of 20 minutes, and at the sulfation reaction temperatures of 270° C. and 300° C. for the sulfation reaction time of 10 minutes.

Experimental Example 3 Analysis of Dissolved Mo Rate According to Sulfation Reaction Temperature and Time

In the method of pre-treating molybdenite containing copper according to the present invention, dissolved Mo rate according to sulfation reaction temperature and time was analyzed and the results were shown in table 6, and FIG. 6.

TABLE 6 Sulfation reaction 180° C. 210° C. 225° C. 240° C. 270° C. 300° C. 10 minutes 0.11 0.1 0.2 0.15 0.23 0.27 20 minutes 0.13 0.12 0.19 0.16 0.15 0.21 30 minutes 0.18 0.14 0.18 0.16 1.17 5.88 40 minutes 0.21 0.18 0.23 0.15 3 8.1 80 minutes 0.18 0.22 0.15 3.49 3.58 8.6

As shown in table 6 and FIG. 6, as the sulfation reaction temperature was raised and the sulfation reaction time was increased, the dissolved Mo rate was increased (H₂SO₄: 32 g, molybdenite: 20 g). In other words, when the sulfation reaction was performed at the temperature of 240° C. for 80 minutes and at the temperature of 270° C. for 30 minutes, the surface of molybdenite was oxidized. Accordingly, if the sulfation reaction time is adjusted in the sulfation reaction temperature of 210° C. to 240° C., Cu can be completely removed without Mo loss. In detail, if the sulfation reaction is performed at the sulfation reaction temperature of 210° C. to 240° C. for the sulfation reaction time of 40 minutes to 80 minutes, Cu can be removed to 99% or more, and Mo can be retrieved to 99.7% or more.

Although the detailed embodiment of the method of pre-treating molybdenite containing copper according to the present invention has been described, it is obvious that various variations and modifications are possible.

Although exemplary embodiments of the present invention have been described for the illustrative purpose, it is understood that the present invention should not be limited to these exemplary embodiments but various changes, modifications, equivalents can be made by one ordinary skilled in the art within the spirit and scope of the present invention as hereinafter claimed. 

What is claimed is:
 1. A method of pre-treating molybdenite containing copper, the method comprising: mixing molybdenite containing copper with sulfuric acid; performing a sulfation reaction through a heating process after the mixing process is performed; performing a water leaching process by putting and stirring water after the sulfation reaction is performed; separating a cake from liquid after the water leaching process is performed; and drying the separated cake.
 2. The method of claim 1, wherein the sulfation reaction is performed at a temperature of 180° C. to 240° C.
 3. The method of claim 1, wherein the sulfation reaction is performed for time of 20 minutes to 80 minutes.
 4. The method of claim 1, wherein the sulfuric acid is mixed with the molybdenite at an equivalent ratio of 0.9 to 1.8 with respect to the molybdenite.
 5. The method of claim 1, wherein the sulfation reaction is performed at a temperature of 180° C. to 240° C. for time of 20 minutes to 80 minutes after the sulfuric acid is mixed at an equivalent ratio of 0.9 to 1.8.
 6. The method of claim 1, wherein the sulfation reaction is performed at a temperature of 210° C. to 240° C.
 7. The method of claim 6, wherein the sulfation reaction is performed for time of 40 minutes to 80 minutes.
 8. The method of claim 6, wherein the sulfuric acid is mixed with the molybdenite at an equivalent ratio of 0.9 to 1.8 with respect to the molybdenite.
 9. The method of claim 1, wherein the sulfation reaction is performed at a temperature of 210° C. to 240° C. for time of 40 minutes to 80 minutes after the sulfuric acid is mixed at an equivalent ratio of 0.9 to 1.8.
 10. The method of claim 1, wherein the water comprises at least one selected from the group consisting of distilled water, deionized water, hard water, and heavy water.
 11. The method of claim 1, further comprising performing a floatation process with respect to the molybdenite before the molybdenite is mixed with the sulfuric acid. 